Petrology of Pierce Canyon Redbeds, Delaware Basin, Texas and New Mexico

Abstract

The Pierce Canyon Formation of the Delaware basin is a brick-red siltstone about 350 feet thick that conformably overlies the Permian Rustler Formation and unconformably underlies the Upper Triassic Santa Rosa Sandstone. Field and laboratory data suggest that the Pierce Canyon is a first-cycle sediment derived from a granitic source in northern Mexico under the influence of an arid climate, transported by the wind, and deposited in a shallow saline lagoon that covered western Texas and southeastern New Mexico at the close of the Permian. In addition, surface and subsurface data from the encompassing strata substantiate the opinion that the Dewey Lake Formation of the southern Permian basin and the Quartermaster Formation of the Texas Panhandle and northwestern Oklahoma have essentially identical mineral assemblages and occupy the same stratigraphic position as the Pierce Canyon. Eight distinct mineralogic differences make it possible to distinguish these formations from the redbeds in the overlying Triassic Dockum Group. The name Pierce Canyon probably should be discontinued in favor of the name Dewey Lake.